融合多数据源的蛋白质功能模块的挖掘算法

针对蛋白质相互作用(protein-protein interaction,PPI)网络的信息不完善和高噪声问题,提出一种融合多生物数据的二分图聚类集成方法以检测网络中的功能模块.该方法结合了基因本体论(gene ontology,GO)、基因表达谱数据以及多种基础聚类算法,用一种新的二分图来组织多种基础聚类算法的中间结果,并结合对称非负矩阵分解(non-negative matrix factorization,NMF)算法挖掘其中功能意义上最一致蛋白质功能模块,同时,该算法能处理蛋白质功能重叠问题.实验结果表明:所提算法整体优于基准比较方法,是一种融合多种生物信息源和不同的聚类方法的有效途径.     

Near-zero-shrinkage Al2O3 ceramic foams with coral-like and hollow-sphere structures via selective laser sintering and reaction bonding

The large shrinkage that ceramics undergo during sintering is a severe challenge for high-performance porous ceramics. In this study, we report a powder-based selective laser sintering (SLS) approach to prepare Al₂O₃ ceramic foams with near-zero shrinkage, high porosity, and outstanding strength. The ceramic foams consist of specific coral-like and hollow-sphere structures derived from the raw Al₂O₃/Al composite powders via reaction bonding (RB). A near-zero shrinkage of 0.91 ± 0.15 % and a high porosity of 73.7 ± 0.2 % can be achieved based on the Kirkendall effect during the oxidation of Al particles. Meanwhile, the reinforced sintering necks and robust bond-bridge connections between hollow-sphere and coral-like structures result in a remarkable bending strength of 7.37 ± 0.37 MPa. This measured strength is more than six times higher than other fabricated samples from spherical Al₂O₃ powders, and the comprehensive performance of ceramic foams prepared by this novel SLS/RB strategy is exceptionally remarkable versus that via conventional forming methods.     

3D FE simulation for temperature evolution in the selective laser sintering process

A thermal model of selective laser sintering (SLS) has been developed. The model allows for the non-linear behavior of thermal conductivity and of specific heat due to temperature changes and phase transformations. The temperature evolution and the formation of the sintered part are simulated by a 3D finite element analysis based on continuous media theory. It is shown that the effect of sintering has a strong influence on thermal evolution through changing the thermal properties of the material. The results of the model were experimentally tested and confirmed by temperature measurements.     

基于FastICA去噪和改进HHT的转子不平衡故障特征提取方法研究

针对转子不平衡振动信号非平稳性并伴随较强环境噪声的特点，提出一种基于快速独立分量分析（FastICA）和改进希尔伯特-黄变换相结合的故障特征提取方法。该方法采用FastICA法去除环境噪声等因素对于故障特征提取精度的影响，再利用自适应白噪声总体平均模态分解方法将故障信号分解为一系列固有模态函数（IMF），并采用基于相似性评估的虚假IMF选择算法将与故障信息无关的虚假IMF分量剔除，从而保证故障信息提取的准确性和有效性。通过仿真分析证明了所提方法的有效性，并且实际试验表明：该方法可有效提取转子不平衡信号的故障特征，为该类故障的诊断提供了一种切实可行的方法。     

间接选择性激光烧结与选择性激光熔化对比研究

采用选择性激光烧结（Selective laser sintering，SLS）和选择性激光熔化（Selective laser melting，SLM）工艺，分别进行了铁基合金粉末的快速成形试验，对比分析了SLS与SLM成形机理、相应的工艺参数以及它们对测试件成形过程、金相组织与力学性能的影响。结果表明：由于成形机理不同，相对于SLS技术，采用SLM能够制造高致密度、组织均匀、力学性能良好的金属零件，但容易出现翘曲变形、裂纹与球化现象。通过制定合适的材料与工艺参数能够避免上述缺陷。     

用选择性声强技术分析车内噪声产生的原因

本文介绍了选择性声强技术在轿车车内噪声识别中的应用。通过对国产轿车在给定工况下的测试分析，确定出试验车发动机仓内最大噪声的位置、司机耳旁辐射噪声产生的原因，为进一步降低该车噪声提供了参考。     

Further studies in selective laser melting of stainless and tool steel powders

Previous reported work on the selective laser melting of a H13 tool steel powder bed surface has shown that there is a scan speed range in which the layer mass increases/fluctuates with increasing speed. This paper expands the investigation towards M2 tool steel and 316L stainless steel powders to identify if they reveal similar behaviours. Wide ranges of scan spacings and scan speeds have been examined, at selected laser powers. Furthermore, the masses of the layers have been compared with those predicted from an existing finite element thermal model. It has been found that at a constant laser power, the variation of mass with scan speed is much less than might be expected from a constant assumed absorptivity into a powder bed.     

一种用于软测量建模的增量学习集成算法

针对软测量模型在实际应用中遇到的问题, 结合AdaBoost 集成学习思想, 提出适用于软测量回归的集成学习算法, 以提高传统软测量模型的精度. 为了克服模型更新技术对软测量实际应用的制约, 将增量学习机制加入软测量集成建模中, 使软测量模型具有在线实时更新的增量学习能力. 对浆纱过程使用新方法建立上浆率软测量模型, 并使用实际生产数据对模型进行检验, 检验结果表明, 该模型具有很好的预测精度, 并能够较好地实现在线更新.

     

结合通道共生和选择集成的彩色图像隐写分析

目的 为了有效对抗针对彩色图像的隐写方案,提出一种新的基于RGB格式的彩色图像隐写分析方法.方法 该方法中的特征包括通道内特征和通道间特征,首先从通道内差分平面上提取共生矩阵特征构成通道内特征集合,通道内特征可以有效捕捉到每一个颜色通道内差分系数之间的相关性;然后对通道与通道相互之间的二次差分平面上提取共生矩阵特征构成通道间特征集合,通道间特征可以捕捉到两两通道之间的相关性.在分类阶段利用遗传算法对多个子分类器进行权值优化,选择权值最优的若干个子分类器,通过众数投票进行集成判决,最终获得最佳的检测性能.结果 针对误检率,提出的通道共生特征比SPAM特征要降低4%~5%,而选择性集成分类器要比完全集成分类器要降低1%~2%.结论 该方法具有较低的时间复杂度,适合小嵌入率的RGB格式彩色图像,在整体性能上优于已有的隐写分析方法.     

Confirmation Bias in Online Searches: Impacts of Selective Exposure Before an Election on Political Attitude Strength and Shifts

Impacts of Internet use on political information seeking and subsequent processes have been subject to much debate. A 2‐session online field study presented online search results on political topics to examine selective exposure and its attitudinal impacts. Session 1 captured attitudes, including their accessibility. Session 2 tracked what online search results participants selected and how long they read them; participants then reported attitudes again. The study represented a 4x8x2x2 within‐subjects design: 4 topics, 8 browsing intervals each, with articles presenting opposing stances, with low versus high source credibility. Attitude‐consistent messages and messages from high‐credibility sources were preferred. Exposure to attitude‐consistent search results increased attitude accessibility and reinforced attitudes, whereas exposure to attitude‐discrepant content had opposite effects, regardless of messages' source credibility.